JP4933071B2 - Cleaning method of silicon wafer - Google Patents
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- JP4933071B2 JP4933071B2 JP2005260402A JP2005260402A JP4933071B2 JP 4933071 B2 JP4933071 B2 JP 4933071B2 JP 2005260402 A JP2005260402 A JP 2005260402A JP 2005260402 A JP2005260402 A JP 2005260402A JP 4933071 B2 JP4933071 B2 JP 4933071B2
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- 238000004140 cleaning Methods 0.000 title claims description 67
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 title claims description 63
- 229910052710 silicon Inorganic materials 0.000 title claims description 63
- 239000010703 silicon Substances 0.000 title claims description 63
- 238000000034 method Methods 0.000 title claims description 32
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 200
- CBENFWSGALASAD-UHFFFAOYSA-N Ozone Chemical compound [O-][O+]=O CBENFWSGALASAD-UHFFFAOYSA-N 0.000 claims description 149
- 229910052751 metal Inorganic materials 0.000 claims description 72
- 239000002184 metal Substances 0.000 claims description 72
- KRHYYFGTRYWZRS-UHFFFAOYSA-N Fluorane Chemical compound F KRHYYFGTRYWZRS-UHFFFAOYSA-N 0.000 claims description 68
- 239000012535 impurity Substances 0.000 claims description 39
- 239000000126 substance Substances 0.000 claims description 34
- 239000000243 solution Substances 0.000 claims description 19
- 238000001035 drying Methods 0.000 claims description 11
- 229910000000 metal hydroxide Inorganic materials 0.000 claims description 5
- 150000004692 metal hydroxides Chemical class 0.000 claims description 5
- 239000011259 mixed solution Substances 0.000 claims description 2
- 235000012431 wafers Nutrition 0.000 description 100
- 239000002245 particle Substances 0.000 description 15
- 238000004519 manufacturing process Methods 0.000 description 10
- 238000011109 contamination Methods 0.000 description 9
- 239000012298 atmosphere Substances 0.000 description 8
- 229910052725 zinc Inorganic materials 0.000 description 7
- 229910052782 aluminium Inorganic materials 0.000 description 6
- 125000002887 hydroxy group Chemical group [H]O* 0.000 description 6
- 238000005406 washing Methods 0.000 description 6
- 230000003749 cleanliness Effects 0.000 description 5
- 229910052742 iron Inorganic materials 0.000 description 5
- 150000002739 metals Chemical class 0.000 description 5
- 230000007935 neutral effect Effects 0.000 description 5
- 230000000694 effects Effects 0.000 description 4
- 238000002474 experimental method Methods 0.000 description 4
- 238000005498 polishing Methods 0.000 description 4
- 229910052791 calcium Inorganic materials 0.000 description 3
- 229910052802 copper Inorganic materials 0.000 description 3
- 238000001095 inductively coupled plasma mass spectrometry Methods 0.000 description 3
- 230000001590 oxidative effect Effects 0.000 description 3
- 239000004065 semiconductor Substances 0.000 description 3
- 229910052708 sodium Inorganic materials 0.000 description 3
- 238000000354 decomposition reaction Methods 0.000 description 2
- 239000000428 dust Substances 0.000 description 2
- 238000005530 etching Methods 0.000 description 2
- 230000033116 oxidation-reduction process Effects 0.000 description 2
- 229910052709 silver Inorganic materials 0.000 description 2
- 239000000758 substrate Substances 0.000 description 2
- 239000003929 acidic solution Substances 0.000 description 1
- 230000002411 adverse Effects 0.000 description 1
- 239000012670 alkaline solution Substances 0.000 description 1
- 239000002738 chelating agent Substances 0.000 description 1
- 229910052804 chromium Inorganic materials 0.000 description 1
- 238000006482 condensation reaction Methods 0.000 description 1
- 230000007423 decrease Effects 0.000 description 1
- 230000018044 dehydration Effects 0.000 description 1
- 238000006297 dehydration reaction Methods 0.000 description 1
- 239000008367 deionised water Substances 0.000 description 1
- 229910021641 deionized water Inorganic materials 0.000 description 1
- 238000009792 diffusion process Methods 0.000 description 1
- 239000003814 drug Substances 0.000 description 1
- 229940079593 drug Drugs 0.000 description 1
- 239000012530 fluid Substances 0.000 description 1
- 238000009616 inductively coupled plasma Methods 0.000 description 1
- 150000002500 ions Chemical class 0.000 description 1
- 239000007788 liquid Substances 0.000 description 1
- 229910052749 magnesium Inorganic materials 0.000 description 1
- 238000012423 maintenance Methods 0.000 description 1
- 239000008155 medical solution Substances 0.000 description 1
- 239000000203 mixture Substances 0.000 description 1
- 229910052759 nickel Inorganic materials 0.000 description 1
- 229910000510 noble metal Inorganic materials 0.000 description 1
- 229910052700 potassium Inorganic materials 0.000 description 1
- 239000004094 surface-active agent Substances 0.000 description 1
- 239000003643 water by type Substances 0.000 description 1
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Description
本発明は、半導体製造工程におけるシリコンウエハの洗浄方法に関し、特にオゾン水を用いたシリコンウエハの洗浄方法に関するものである。 The present invention relates to a silicon wafer cleaning method in a semiconductor manufacturing process, and more particularly to a silicon wafer cleaning method using ozone water.
半導体製造工程において、シリコンウエハは、製造装置からの汚染、クリーンルーム中の雰囲気からの汚染など、製造プロセス中にさまざまな汚染を受ける可能性を有している。これらの汚染を除去するため、シリコンウエハは、製造各プロセスの前後においてウェット洗浄されている。 In a semiconductor manufacturing process, a silicon wafer has a possibility of being subjected to various contaminations during the manufacturing process such as contamination from a manufacturing apparatus and contamination from an atmosphere in a clean room. In order to remove these contaminations, silicon wafers are wet cleaned before and after each manufacturing process.
近年、そのウェット洗浄の洗浄水として、常温、少量添加でも、高い酸化力が得られるオゾン水が注目され、清浄なオゾン水が製造できるオゾン水製造装置が開発され、シリコンウエハの洗浄にオゾン水が広く利用されるようになってきている。 In recent years, ozone water that can obtain high oxidizing power even when added in a small amount at room temperature is attracting attention as cleaning water for wet cleaning, and an ozone water production apparatus capable of producing clean ozone water has been developed. Are becoming widely used.
そして、最近では、特許文献１，２に示されているように、オゾン水と希フッ酸だけを用い、室温で洗浄する方法が提案されている。
この提案された洗浄方法にあっては、まず、第１ステップとして、オゾン水をウエハの表面に供給し、オゾン水によってウエハの表面に付着している有機物を分解・除去すると共にウエハの表面にケミカル酸化膜を形成する。
次に、第２ステップとして、希フッ酸をウエハの表面に供給し、希フッ酸により前記酸化膜をエッチング除去して酸化膜中あるいは酸化膜上の金属系ゴミとパーティクルをウエハの表面から取り除く。
そして、求める清浄度に応じて、これら第１、第２のステップを繰り返す。
Recently, as disclosed in Patent Documents 1 and 2, a method of cleaning at room temperature using only ozone water and dilute hydrofluoric acid has been proposed.
In the proposed cleaning method, first, as a first step, ozone water is supplied to the surface of the wafer, and the organic substances adhering to the surface of the wafer are decomposed and removed by the ozone water, and the surface of the wafer is also removed. A chemical oxide film is formed.
Next, as a second step, dilute hydrofluoric acid is supplied to the surface of the wafer, and the oxide film is removed by etching with dilute hydrofluoric acid to remove metal dust and particles in or on the oxide film from the surface of the wafer. .
Then, these first and second steps are repeated according to the required cleanliness.
このように、オゾン水、フッ酸を用いた処理を行なった後に、純水を用いた、いわゆる純水リンスを行なう。その後、ウエハを高速回転させ、スピン乾燥することにより、ウエハの洗浄が終了する。 Thus, after performing the treatment using ozone water and hydrofluoric acid, so-called pure water rinsing using pure water is performed. Thereafter, the wafer is rotated at a high speed and spin-dried to complete the cleaning of the wafer.
また、特許文献３には、基板の表面を薬品処理した後、オゾン水を用いた、いわゆるオゾン水リンスを行ない、続けて純水リンスを行なう洗浄方法が提案されている。
この提案された洗浄方法にあっては、薬品処理後にオゾン水リンスを行なうことで、オゾンの強い酸化力を利用して、ウエハ表面に化学結合した薬液成分を効果的に除去すると共に、ウエハ表面に酸化膜が形成される。
そして、前記オゾン水リンスに続けて純水リンスを行なうことで、酸化膜の表面に水酸基（ＯＨ）がターミネートされると共にウエハ表面のオゾン水が除去される。
Patent Document 3 proposes a cleaning method in which a so-called ozone water rinse using ozone water is performed after chemical treatment of the surface of the substrate, followed by a pure water rinse.
In this proposed cleaning method, rinsing with ozone water after chemical treatment effectively removes chemical components chemically bonded to the wafer surface using the strong oxidizing power of ozone, and the wafer surface. An oxide film is formed.
Then, by rinsing with pure water after the rinsing with ozone water, hydroxyl groups (OH) are terminated on the surface of the oxide film and ozone water on the wafer surface is removed.
一方、ウェット洗浄する際、一般的にスピン洗浄法が用いられている。このスピン洗浄法をオゾン水及びフッ酸を用いた場合について説明する。
このスピン洗浄法は、ウエハを回転させながら洗浄を行なうものであって、まず、回転するウエハにオゾン水を塗布してケミカル酸化膜を形成し、更に希フッ酸を塗布して酸化膜のエッチング除去を行ない、これらを交互に繰り返すことで、ウエハ表面の金属不純物およびパーティクルを除去する。その後、オゾン水で酸化膜を形成し、純水リンスした後、高速回転して乾燥する。
On the other hand, when performing wet cleaning, a spin cleaning method is generally used. This spin cleaning method will be described using ozone water and hydrofluoric acid.
This spin cleaning method performs cleaning while rotating the wafer. First, ozone water is applied to the rotating wafer to form a chemical oxide film, and further diluted hydrofluoric acid is applied to etch the oxide film. Removal is performed and these are alternately repeated to remove metal impurities and particles on the wafer surface. Thereafter, an oxide film is formed with ozone water, rinsed with pure water, and then rotated at high speed and dried.
ところで、前記した特許文献１，２，３、のいずれも最終工程で、いわゆる純水リンスを行なっている。このとき純水リンスにおいて、純水中に金属不純物を僅かでも含んでいると、シリコンウエハの表面に金属不純物が付着するという技術的課題があった。 By the way, all of above-mentioned patent documents 1, 2, and 3 perform what is called pure water rinse in the last process. At this time, in the pure water rinse, if the pure water contains even a small amount of metal impurities, there is a technical problem that the metal impurities adhere to the surface of the silicon wafer.
これは純水がｐＨ７の中性溶液であり、金属はｐＨ７以上の中性〜アルカリ性溶液中では非常に付着し易いという性質があるためである。シリコンウエハの純水リンス中に付着し易い金属は、ウエハの表面状態（ベアシリコン表面、酸化膜表面）によって異なり、ＣｕおよびＡｇ等貴金属はベアシリコン表面の方が酸化膜表面よりも付着し易く、Ｚｎ、Ｆｅ、およびＡｌ等の金属水酸化物は酸化膜表面の方が付着し易い。 This is because pure water is a neutral solution at pH 7, and metal has a property that it is very easy to adhere in neutral to alkaline solutions at pH 7 or higher. The metal that easily adheres to the pure water rinse of the silicon wafer differs depending on the wafer surface condition (bare silicon surface, oxide film surface), and the noble metal such as Cu and Ag adheres more easily on the bare silicon surface than the oxide film surface. Metal hydroxides such as Zn, Fe, and Al are more likely to adhere to the oxide film surface.
特に、Ａｌ、ＦｅおよびＺｎといった金属は、ｐＨ７以上の溶液中においてＯＨ基と結合して金属水酸化物となっている。シリコンウエハの酸化膜表面は中性〜アルカリ性領域においてＳｉと結合したＯＨ基で覆われており、純水中では金属と結合したＯＨ基と、ＳｉのＯＨ基との間で脱水縮合反応が起こり、金属はシリコンウエハ表面に付着する。 In particular, metals such as Al, Fe, and Zn are combined with OH groups in a solution having a pH of 7 or more to form metal hydroxides. The oxide film surface of the silicon wafer is covered with OH groups bonded to Si in the neutral to alkaline region, and in deionized water, a dehydration condensation reaction takes place between the OH groups bonded to the metal and the OH groups of Si. The metal adheres to the silicon wafer surface.
一方、純水は、通常、フィルタにより純水中のパーティクルや金属不純物を除去してシリコンウエハの洗浄液として使用する。しかし、フィルタの高性能化が進んでいるものの、フィルタを通過した純水中において金属や微小サイズのパーティクルが完全に除去されることはなく、非常に極微量の金属やフィルタのろ過精度以下の微小サイズパーティクルを含んでいる。また、配管の汚染やメンテナンス時の汚染等が純水中に溶け込み洗浄後のウエハに悪影響を及ぼすこともある。 On the other hand, pure water is usually used as a cleaning solution for silicon wafers by removing particles and metal impurities from the pure water using a filter. However, although the performance of filters has been improved, metals and micro-sized particles are not completely removed in the pure water that has passed through the filters. Contains small size particles. In addition, contamination of piping, contamination during maintenance, etc. may dissolve in pure water and adversely affect the wafer after cleaning.
更に、洗浄を行なうチャンバ内の雰囲気に金属不純物を僅かでも含んでいると、雰囲気中から純水中に金属不純物が溶け込んで、純水リンス時にシリコンウエハ表面に金属不純物が付着する。
また、チャンバ内の雰囲気についても、通常エアーフィルタにより大気中のパーティクルを除去するが、エアーフィルタを通過した空気でもフィルタのメッシュサイズ以下の極微小パーティクルや金属含有パーティクルを含んでいる。
このため、シリコンウエハを純水リンスした場合、ウエハ表面の状態がベアシリコン表面でも酸化膜表面でも極微小な金属が付着してしまう。
Further, if the atmosphere in the chamber to be cleaned contains even a small amount of metal impurities, the metal impurities dissolve into the pure water from the atmosphere, and the metal impurities adhere to the silicon wafer surface during the pure water rinse.
Also, as for the atmosphere in the chamber, particles in the atmosphere are usually removed by an air filter, but the air that has passed through the air filter also contains very small particles or metal-containing particles that are smaller than the mesh size of the filter.
For this reason, when the silicon wafer is rinsed with pure water, a very small amount of metal adheres regardless of whether the wafer surface is in the bare silicon surface or the oxide film surface.
また、前記したように、スピン回転するシリコンウエハに純水を塗布した場合、シリコンウエハの表面近傍では純水はシリコンウエハと一緒に回転運動する。これは回転する円板上の流体の運動に例えることができる。このとき、円板から無限大に離れた点では流速は円板上方成分のみ存在し、円板付近の応力が半径方向に依存しないという仮定をおくと、速度境界層（流体本体と速度が大きく異なる層）の厚さδは次のような式で表現される（コックラン流）。
この式から明らかなように、回転数の増加と共に金属の付着に寄与する境界層の厚さが薄くなる。このため、境界層における純水中に僅かにでも金属を含有していると、純水中の金属の拡散現象によりシリコンウエハ表面における金属の濃度が高くなる。
特に、枚葉式のスピン洗浄では１００〜５００ｒｐｍでシリコンウエハを回転させるため、境界層は非常に薄く、純水中に極僅かに含んだ金属でも非常に付着し易い状態となる。
As is apparent from this equation, the thickness of the boundary layer that contributes to the adhesion of the metal decreases as the rotational speed increases. For this reason, if the pure water in the boundary layer contains even a slight amount of metal, the metal concentration on the surface of the silicon wafer increases due to the diffusion phenomenon of the metal in the pure water.
In particular, in the single wafer type spin cleaning, since the silicon wafer is rotated at 100 to 500 rpm, the boundary layer is very thin, and even a very small amount of metal in pure water is very easily attached.
上記説明したように、シリコンウエハの洗浄において、薬液処理後に純水リンスを行なった場合、
（１）純水は中性（ｐＨ７）のため、酸化膜表面では金属水酸化物となったＡｌ，Ｆｅ，およびＺｎといった金属が付着し易く、ベアシリコン表面ではＣｕ，およびＡｇといった金属が付着し易いという課題があった。
（２）また、洗浄方式としてスピン洗浄法を用いた場合、シリコンウエハのスピン回転により金属の付着に寄与する境界層の厚さが薄くなり、シリコンウエハ表面における金属濃度が高くなるため、純水中に極僅かに含んだ金属でもシリコンウエハに付着し易いという技術的課題があった。
As described above, in the cleaning of the silicon wafer, when pure water rinsing is performed after chemical treatment,
(1) Since pure water is neutral (pH 7), metals such as Al, Fe, and Zn, which have become metal hydroxides, easily adhere to the oxide film surface, and metals such as Cu and Ag adhere to the bare silicon surface. There was a problem that it was easy to do.
(2) Also, when the spin cleaning method is used as the cleaning method, the thickness of the boundary layer contributing to metal adhesion is reduced by the spin rotation of the silicon wafer, and the metal concentration on the silicon wafer surface is increased. There is a technical problem that even a very small amount of metal is easily attached to a silicon wafer.
本発明は、前記技術的課題を解決するためになされたものであり、スピン洗浄を用いた場合であっても、ウエハ表面の金属不純物を除去でき、清浄度の高いウエハの洗浄方法を提供することを目的とする。 The present invention has been made to solve the above technical problem, and provides a high-cleanness wafer cleaning method that can remove metal impurities on the wafer surface even when spin cleaning is used. For the purpose.
本発明は上記目的を達成するためになされたものであって、本発明にかかるシリコンウエハの洗浄方法は、オゾン水と希フッ酸を交互に塗布して、またはＮＨ ４ ＯＨとＨ ２ Ｏ ２ とＨ ２ Ｏの混合液を用いてシリコンウエハを洗浄する工程と、前記シリコンウエハを洗浄する工程の後、前記薬液を用いて洗浄されたシリコンウエハの表面をオゾン水でリンスすることにより、前記シリコンウエハ表面に酸化膜を形成する第１のオゾン水リンス工程と、前記第１のオゾン水リンス工程の後、前記第１のオゾンリンス工程で形成された酸化膜表面を純水でリンスする純水リンス工程と、前記純水でリンスした後、純水でリンスされた酸化膜表面を再びオゾン水でリンスすることによって、前記純水リンス工程においてウエハの酸化膜表面で金属水酸化物となった金属不純物を除去する第２のオゾン水リンス工程と、前記第２のオゾン水リンス工程の後、前記金属不純物が除去されたシリコンウエハを乾燥する乾燥工程と、を含むことを特徴としている。 The present invention has been made in order to achieve the above object, and a silicon wafer cleaning method according to the present invention comprises applying ozone water and dilute hydrofluoric acid alternately, or NH 4 OH and H 2 O 2. After washing the silicon wafer with a mixed solution of H 2 O and the step of washing the silicon wafer, the surface of the silicon wafer washed with the chemical solution is rinsed with ozone water, A first ozone water rinsing process for forming an oxide film on the silicon wafer surface, and a pure water rinsing the oxide film surface formed in the first ozone rinsing process with pure water after the first ozone water rinsing process. In the water rinsing step, after rinsing with pure water, the surface of the oxide film rinsed with pure water is rinsed again with ozone water. A second ozone water rinsing step for removing metal impurities that have become oxides, and a drying step for drying the silicon wafer from which the metal impurities have been removed after the second ozone water rinsing step. It is a feature.
このように、所定の薬液処理後、洗浄工程の最終段階で、オゾン水でリンスし、その後純水でリンスし、更に、再度オゾン水でリンスする。そしてオゾン水でリンスした後、シリコンウエハの乾燥を行なう。
本発明にあっては、薬液処理後オゾン水でリンスしているため、ウエハ表面の薬液を除去できると共に、シリコンウエハ表面に酸化膜が形成される。そして、オゾン水を用いたリンスに続けて純水を用いたリンスを行うことで、酸化膜の表面に水酸基がターミネートされる。このとき、純水に僅かな金属不純物が含まれていると、その金属はシリコンウエハの表面に付着するが、再び、オゾン水でリンスすることにより前記金属不純物は除去され、清浄度の高いウエハを得ることができる。
As described above, after a predetermined chemical solution treatment, rinsing with ozone water is performed at the final stage of the cleaning process, followed by rinsing with pure water, and further rinsing with ozone water. Then, after rinsing with ozone water, the silicon wafer is dried.
In the present invention, since the chemical solution is rinsed with ozone water after the chemical treatment, the chemical solution on the wafer surface can be removed and an oxide film is formed on the silicon wafer surface. Then, the hydroxyl group is terminated on the surface of the oxide film by rinsing with pure water following rinsing with ozone water. At this time, if the pure water contains a slight amount of metal impurities, the metal adheres to the surface of the silicon wafer, but the metal impurities are removed by rinsing with ozone water again, and the wafer has a high cleanliness. Can be obtained.
ここで、前記第１、２のオゾン水リンス工程において用いられるオゾン水に含まれるオゾン量が、５ｐｐｍ以上５０ｐｐｍ以下であることが望ましい。
前記第１のオゾン水リンスにおいて、オゾン水濃度が５ｐｐｍ未満では、安定したケミカル酸化膜を形成するのに３０秒以上要するため好ましくない。さらに、前記第２のオゾン水リンスにおいて、オゾン濃度が５ｐｐｍ未満では、酸化還元電位が十分に高くならず、金属の除去能力が発揮できなくなるため好ましくない。またオゾン濃度が５０ｐｐｍを超えるとオゾン水製造装置でオゾン濃度を高めて安定させるまでの時間がかかり過ぎ、またオゾンの分解が激しくなるためにオゾン水の使用前に配管中で多量の気泡が発生したり、槽内で多量の気泡が発生したりして洗浄ムラやパーティクル付着が起こるため好ましくない。なお、前記第１、第２のオゾン水は必ずしも同一のオゾン水である必要はなく、オゾン水に含まれるオゾン量が異なるものであっても良い。
Here, it is desirable that the amount of ozone contained in the ozone water used in the first and second ozone water rinsing steps is 5 ppm or more and 50 ppm or less.
If the ozone water concentration is less than 5 ppm in the first ozone water rinse, it is not preferable because it takes 30 seconds or more to form a stable chemical oxide film. Further, in the second ozone water rinse, if the ozone concentration is less than 5 ppm, the oxidation-reduction potential is not sufficiently high, and the metal removal ability cannot be exhibited, which is not preferable. Also, if the ozone concentration exceeds 50 ppm, it takes too much time to increase and stabilize the ozone concentration in the ozone water production system, and the decomposition of ozone becomes severe, so a lot of bubbles are generated in the piping before using the ozone water. Or a large amount of bubbles are generated in the tank, resulting in uneven cleaning and particle adhesion. Note that the first and second ozone waters are not necessarily the same ozone water, and the ozone amounts contained in the ozone water may be different.
上記のように、本発明のシリコンウエハの洗浄方法によれば、希フッ酸やＡＰＭといった薬液を除去する洗浄処理の最終工程で、オゾン水、純水、オゾン水を用いてリンスすることにより、前記薬液を除去すると共に、表面金属不純物の付着を抑制し、且つ付着した表面金属不純物を除去することができる。また、本発明のシリコンウエハの洗浄方法によれば、スピン洗浄法を用いても清浄度の高いウエハを得ることができる。 As described above, according to the silicon wafer cleaning method of the present invention, by rinsing with ozone water, pure water, or ozone water in the final step of the cleaning process for removing a chemical solution such as dilute hydrofluoric acid or APM, While removing the said chemical | medical solution, adhesion of a surface metal impurity can be suppressed and the attached surface metal impurity can be removed. Further, according to the silicon wafer cleaning method of the present invention, a wafer having a high cleanliness can be obtained even by using a spin cleaning method.
本発明にかかるシリコンウエハの洗浄方法の実施形態について、図１に基づいて説明する。この図１に示した洗浄方法は、薬液としてオゾン水と希フッ酸を交互に塗布して洗浄する方法を示している。前記薬液にキレート剤や界面活性剤を添加しても良い。
まず、第１ステップ（Ｓ１）として、オゾン水をウエハの表面に供給し、オゾン水によってウエハの表面に付着している有機物を分解・除去すると共にウエハの表面にケミカル酸化膜を形成する。
次に、第２ステップ（Ｓ２）として、希フッ酸をウエハの表面に供給し、希フッ酸により前記酸化膜をエッチング除去して酸化膜中あるいは酸化膜上の金属系ゴミとパーティクルをウエハの表面から取り除く。
更に、求める清浄度に応じて、これら第１、第２のステップを繰り返す。
An embodiment of a silicon wafer cleaning method according to the present invention will be described with reference to FIG. The cleaning method shown in FIG. 1 shows a cleaning method by alternately applying ozone water and dilute hydrofluoric acid as a chemical solution. A chelating agent or a surfactant may be added to the chemical solution.
First, as a first step (S1), ozone water is supplied to the surface of the wafer, organic substances adhering to the surface of the wafer are decomposed and removed by the ozone water, and a chemical oxide film is formed on the surface of the wafer.
Next, as a second step (S2), dilute hydrofluoric acid is supplied to the surface of the wafer, and the oxide film is removed by etching with dilute hydrofluoric acid to remove metallic dust and particles in or on the oxide film on the wafer. Remove from the surface.
Further, the first and second steps are repeated according to the required cleanliness.
そして、前記薬液（オゾン水と希フッ酸）による洗浄により、半導体基板のパーティクルや金属不純物を除去した後、第３のステップ（Ｓ３）として、オゾン水をウエハの表面に供給し、オゾン水によってウエハの表面をリンスする。このオゾン水によってウエハの表面に付着している有機物を分解・除去すると共にウエハの表面にケミカル酸化膜を形成する。 Then, after removing particles and metal impurities from the semiconductor substrate by cleaning with the chemical solution (ozone water and dilute hydrofluoric acid), as a third step (S3), ozone water is supplied to the surface of the wafer. Rinse the surface of the wafer. The ozone water decomposes and removes organic substances adhering to the wafer surface and forms a chemical oxide film on the wafer surface.
そして、第４のステップ（Ｓ４）として、シリコンウエハ表面に付着するオゾン水を純水リンスして洗い流す。 Then, as a fourth step (S4), the ozone water adhering to the silicon wafer surface is rinsed with pure water and washed away.
この純水リンスの後、第５のステップ（Ｓ５）として、再び、オゾン水リンスを行なう。このオゾン水リンスは、前記した純水リンスステップで、ウエハに付着した金属付着物を除去するためになされる。即ち、純水は中性（ｐＨ７）のため、酸化膜表面では金属水酸化物となったＡｌ，Ｆｅ，およびＺｎといった金属が付着し易い。そのため、前記純水リンスに用いた純水中に含まれていた金属不純物、あるいはチャンバ内の雰囲気の金属不純物がウエハ表面に付着し易いが、このオゾン水をリンス行なうことにより、前記金属不純物は除去される。 After this pure water rinse, ozone water rinse is performed again as a fifth step (S5). This ozone water rinsing is performed in order to remove metal deposits adhering to the wafer in the pure water rinsing step. That is, since pure water is neutral (pH 7), metals such as Al, Fe, and Zn that have become metal hydroxides are likely to adhere to the oxide film surface. Therefore, metal impurities contained in the pure water used for the pure water rinse or metal impurities in the atmosphere in the chamber are likely to adhere to the wafer surface. By rinsing the ozone water, the metal impurities are Removed.
その後、第５のステップ（Ｓ５）として、シリコンウエハを乾かすため、スピン乾燥やＩＰＡによるマランゴニ乾燥といった乾燥方法で乾燥する。 Thereafter, in a fifth step (S5), the silicon wafer is dried by a drying method such as spin drying or Marangoni drying by IPA.
また、前記実施形態にあっては、薬液としてオゾン水と希フッ酸を用いた場合について説明したが、他の薬液としてＡＰＭ（ＮＨ4ＯＨとＨ2Ｏ2とＨ2Ｏの混合液）を用いても良い。この場合、図２に示すように、まず、第１のステップ（Ｓ１）としてＡＰＭをウエハの表面に供給し、ＡＰＭによってウエハの表面に付着しているパーティクルを除去する。
続いて、第２のステップ（Ｓ２）として、オゾン水をウエハの表面に供給し、オゾン水リンスを行なう。このオゾン水によってウエハの表面に付着している金属不純物が除去されると共にウエハの表面にケミカル酸化膜が形成される。
Further, the In the embodiment has described the case of using the ozone water and dilute hydrofluoric acid as the chemical, the APM (NH 4 OH and H 2 O 2 and H 2 O mixture) as another drug solution It may be used. In this case, as shown in FIG. 2, first, as a first step (S1), APM is supplied to the surface of the wafer, and particles adhering to the surface of the wafer are removed by APM.
Subsequently, as a second step (S2), ozone water is supplied to the surface of the wafer, and ozone water rinsing is performed. This ozone water removes metal impurities adhering to the wafer surface and forms a chemical oxide film on the wafer surface.
前記したようにウエハのパーティクルや金属不純物を除去した後、第３のステップ（Ｓ３）として、シリコンウエハ表面に付着するオゾン水を純水リンスして洗い流す。
この純水リンスの後、第４のステップ（Ｓ４）として、前記した実施形態と同様に、オゾン水リンスを再び行なう。
その後、第５のステップとして、シリコンウエハを乾かすため、スピン乾燥やＩＰＡによるマランゴニ乾燥といった乾燥方法で乾燥する。
As described above, after removing the wafer particles and metal impurities, as a third step (S3), the ozone water adhering to the silicon wafer surface is rinsed with pure water and washed away.
After the pure water rinse, as the fourth step (S4), the ozone water rinse is performed again as in the above-described embodiment.
Thereafter, as a fifth step, the silicon wafer is dried by a drying method such as spin drying or Marangoni drying by IPA.
本発明にかかる洗浄方法におけるオゾン水リンスは純水リンスに比べ、シリコンウエハ表面に金属不純物が付着しにくい特徴を持ち、薬液を洗い流すためのリンスとシリコンウエハ表面に付着した金属を除去する洗浄の効果を併せ持つ。 Compared with pure water rinse, the ozone water rinse in the cleaning method according to the present invention has a feature that metal impurities are less likely to adhere to the surface of the silicon wafer. The rinse for washing away the chemical solution and the metal adhered to the surface of the silicon wafer It also has an effect.
しかも、前記オゾン水は約ｐＨ６の弱酸性溶液であるため、上記述べた理由から純水に比べシリコンウエハ表面の酸化膜上に金属が付着し難い。また、オゾン水はシリコンウエハ表面の金属不純物の除去が可能である。例え純水リンスによりシリコンウエハが金属汚染されたとしても、オゾン水リンスにより除去可能である。 Moreover, since the ozone water is a weakly acidic solution having a pH of about 6, metal is less likely to adhere on the oxide film on the silicon wafer surface than pure water for the reasons described above. Ozone water can remove metal impurities on the surface of the silicon wafer. Even if the silicon wafer is contaminated with metal by pure water rinse, it can be removed by ozone water rinse.
したがって、一度目のオゾン水リンスは、主に薬液及び金属付着物を流すと共に安定した酸化膜を形成するものであり、二度目のオゾン水リンスは、主にウエハ表面に付着した金属を除去すると共に金属が付着し難い表面状態になすためになされる。 Therefore, the first ozone water rinse mainly flows a chemical solution and metal deposits and forms a stable oxide film, and the second ozone water rinse mainly removes the metal adhered to the wafer surface. At the same time, it is made to achieve a surface state in which metal is difficult to adhere.
オゾン水のリンス性能については、一度目のオゾン水リンスに用いられるオゾン水と、二度目のオゾン水リンスに用いられるオゾン水は、同一のものが用いられる。なお、必ずしも、同一のオゾン水でなくても良い。
このオゾン水のリンス性能については、上記したようにオゾンの強い酸化力を利用してシリコンウエハ表面に化学結合した薬液成分を効果的に除去すると共に、安定したケミカル酸化膜を形成する。オゾン水は純水にオゾンガスを添加して製造されることから、オゾンガスが抜ければ純水となるため、通常の純水リンスによる薬液を洗い流す効果と同様な効果がある。
Regarding the rinsing performance of ozone water, the same ozone water is used as the ozone water used for the first ozone water rinsing and the ozone water used for the second ozone water rinsing. The ozone water is not necessarily the same.
As for the rinsing performance of the ozone water, the chemical component chemically bonded to the silicon wafer surface is effectively removed and a stable chemical oxide film is formed using the strong oxidizing power of ozone as described above. Since ozone water is produced by adding ozone gas to pure water, it becomes pure water when ozone gas is removed. Therefore, there is an effect similar to the effect of washing away a chemical solution by normal pure water rinsing.
前記オゾン水リンス時のオゾン濃度は、５ｐｐｍ以上であることが望ましく、好ましくは１０〜３０ｐｐｍである。オゾン濃度が５ｐｐｍ未満では、酸化還元電位が十分に高くならず、金属の除去能力が発揮できなくなるため好ましくない。金属除去能力の観点から言えば、オゾン濃度の上限は特に規定するものではないが、５０ｐｐｍ以下であることが望ましい。５０ｐｐｍを超えるとオゾン水製造装置でオゾン濃度を高めて安定させるまでの時間がかかり過ぎ、またオゾンの分解が激しくなるためにオゾン水の使用前に配管中で多量の気泡が発生したり、槽内で多量の気泡が発生したりして洗浄ムラやパーティクル付着が起こる虞があるからである。 The ozone concentration during the rinsing with ozone water is desirably 5 ppm or more, and preferably 10 to 30 ppm. If the ozone concentration is less than 5 ppm, the oxidation-reduction potential is not sufficiently high, and the metal removal ability cannot be exhibited, which is not preferable. From the viewpoint of metal removal capability, the upper limit of the ozone concentration is not particularly specified, but is desirably 50 ppm or less. If it exceeds 50 ppm, it takes too much time to increase and stabilize the ozone concentration in the ozone water production device, and since the decomposition of ozone becomes intense, a large amount of bubbles are generated in the piping before using the ozone water, and the tank This is because there is a possibility that a large amount of bubbles are generated in the inside, and cleaning unevenness or particle adhesion may occur.
前記オゾン水リンス液の温度は、特に限定するものではないが、望ましくは１０〜３０度である。洗浄温度を低下させ過ぎると、リンスおよび洗浄効率が低下する可能性がある。一方、洗浄温度を上げ過ぎると、リンスおよび洗浄効率は向上するものの、オゾンの溶解濃度が確保できなくなる虞がある。 The temperature of the ozone water rinsing liquid is not particularly limited, but is preferably 10 to 30 degrees. If the cleaning temperature is lowered too much, rinsing and cleaning efficiency may be reduced. On the other hand, if the cleaning temperature is raised too much, rinsing and cleaning efficiency are improved, but there is a possibility that the ozone concentration cannot be ensured.
また、一度目のオゾン水リンス時間はそれ以前に処理していた薬液のリンス時間、すなわち置換時間と、安定したケミカル酸化膜が形成されるまでの時間とを目安とし、二度目のオゾン水リンス時間は、純水で付着した金属不純物が除去できる時間を目安とする。
具体的に説明すると、オゾン水リンス時間は、特に限定するものでないが、枚葉式スピン洗浄の場合は５〜３０秒、バッチ式洗浄の場合は、１〜１５分である。特に１度目のオゾン水において安定した酸化膜が形成される時間は２０ｐｐｍのオゾン水を用いた場合１０秒程度である。また、バッチ式洗浄の場合は、槽内のオゾン水を１回以上置換する時間は１分程度であり、薬液の置換時間を考慮すると１分以上が必要である。このため、リンス時間が短すぎると、１度目のオゾン水においては安定した酸化膜が形成されない、薬液がリンスされない可能性があり、２度目のオゾン水においてはリンスおよび洗浄能力が十分発揮できない可能性がある。一方、リンス時間が長過ぎても金属除去に関しては特に不都合を生じないが、他の工程の洗浄時間を上回るとプロセスとして非効率となるため、枚葉式スピン洗浄の場合は３０秒以下、バッチ式洗浄の場合は１５分以下であることが望ましい。
The ozone water rinse time for the first time is based on the rinse time of the chemical solution processed before that, that is, the replacement time and the time until a stable chemical oxide film is formed. The time is taken as a rough standard for removing the metal impurities attached with pure water.
Specifically, the ozone water rinsing time is not particularly limited, but it is 5 to 30 seconds in the case of single wafer spin cleaning, and 1 to 15 minutes in the case of batch cleaning. In particular, the time for forming a stable oxide film in the first ozone water is about 10 seconds when 20 ppm ozone water is used. In the case of batch cleaning, the time for replacing ozone water in the tank once or more is about 1 minute, and 1 minute or more is necessary in consideration of the replacement time of the chemical solution. For this reason, if the rinsing time is too short, a stable oxide film may not be formed in the first ozone water, the chemical solution may not be rinsed, and the rinsing and cleaning ability may not be sufficiently exhibited in the second ozone water. There is sex. On the other hand, even if the rinsing time is too long, there is no particular inconvenience with regard to metal removal, but if the cleaning time of other steps is exceeded, the process becomes inefficient, so in the case of single-wafer spin cleaning, it takes 30 seconds or less In the case of the type cleaning, it is desirable that it is 15 minutes or less.
以下、枚葉式スピン洗浄による純水リンスでの汚染と表面金属不純物除去能力について説明する。ここで用いた枚葉式スピン洗浄装置における純水あるいはスピン処理槽内の雰囲気は、いずれも市販の純水フィルタあるいはエアーフィルタを用いて、清浄度を高めている。また、前記純水と同じ純水を用いてオゾン水製造装置によりオゾン水を製造し洗浄装置へ供給している。 Hereinafter, contamination with pure water rinse by single wafer spin cleaning and surface metal impurity removal capability will be described. The pure water in the single wafer type spin cleaning apparatus used here or the atmosphere in the spin processing tank is improved in cleanliness by using a commercially available pure water filter or air filter. Further, ozone water is produced by an ozone water production apparatus using the same pure water as the pure water and supplied to the cleaning apparatus.
〔実験例１〕
まず、枚葉式スピン洗浄における純水リンスでの汚染について実験を行なった。
最終仕上げ研磨が成されたφ３００ｍｍシリコンウエハを、枚葉式スピン洗浄装置により濃度２０ｐｐｍのオゾン水と濃度１重量％の希フッ酸を用いて、各１０秒でオゾン水と希フッ酸とを３回交互に繰り返す洗浄（オゾン水／希フッ酸／オゾン水／希フッ酸／オゾン水／希フッ酸）を行なった。
その後、更に上記濃度のオゾン水洗浄を１０秒行ない、表面に酸化膜を形成した後、純水リンスをそれぞれ０秒、５秒、３０秒、６０秒、３００秒、および９００秒行ない、高速スピン回転により乾燥させた。
[Experimental Example 1]
First, an experiment was conducted on contamination with pure water rinse in single wafer spin cleaning.
The φ300 mm silicon wafer on which the final finish polishing has been performed is performed by using a single wafer type spin cleaning apparatus to add ozone water and dilute hydrofluoric acid in 10 seconds each using 10 ppm ozone water and 1 wt% dilute hydrofluoric acid. The cleaning was repeated alternately (ozone water / dilute hydrofluoric acid / ozone water / dilute hydrofluoric acid / ozone water / dilute hydrofluoric acid).
Thereafter, cleaning with ozone water of the above concentration is further performed for 10 seconds, and after forming an oxide film on the surface, pure water rinsing is performed for 0 seconds, 5 seconds, 30 seconds, 60 seconds, 300 seconds, and 900 seconds, respectively. Dry by rotation.
前記のように処理したシリコンウエハについて、それぞれＩＰＣ−ＭＳ（誘導結合プラズマイオン源質量分析装置）により表面金属不純物濃度を調べた。表１に、表面のＮａ，Ｋ，Ｃａ，Ｃｕ，Ｆｅ，Ｎｉ，Ｃｒ，Ａｌ，Ｍｇ，Ｚｎ濃度と純水リンス時間との関係を調べた結果を示す。
この表１の結果からわかるように、純水リンス時間が長くなると、表面の金属不純物Ｎａ，Ｃａ，ＡｌおよびＺｎ濃度が増加した。これは、純水リンス時に純水中あるいは雰囲気中の金属不純物が純水中に溶け込んで、付着したものと考えられる。
The silicon wafers treated as described above were examined for surface metal impurity concentrations by IPC-MS (inductively coupled plasma ion source mass spectrometer). Table 1 shows the results of examining the relationship between the Na, K, Ca, Cu, Fe, Ni, Cr, Al, Mg, and Zn concentrations on the surface and the pure water rinse time.
As can be seen from the results in Table 1, the concentration of metal impurities Na, Ca, Al and Zn on the surface increased as the pure water rinse time increased. This is presumably because metal impurities in pure water or the atmosphere dissolved and adhered to the pure water during rinsing with pure water.
〔実験例２〕
次に、オゾン水リンスによる表面金属汚染の除去について実験を行なった。
前記実験例１と同様に、最終仕上げ研磨が成されたφ３００ｍｍシリコンウエハを、枚葉式スピン洗浄装置により濃度２０ｐｐｍのオゾン水と濃度１重量％の希フッ酸を用いて、各１０秒でオゾン水と希フッ酸とを３回交互に繰り返す洗浄（オゾン水／希フッ酸／オゾン水／希フッ酸／オゾン水／希フッ酸）を行なった。
[Experimental example 2]
Next, an experiment was conducted to remove surface metal contamination by rinsing with ozone water.
In the same manner as in Experimental Example 1, a φ300 mm silicon wafer subjected to final finish polishing was subjected to ozone in 10 seconds each using ozone water with a concentration of 20 ppm and dilute hydrofluoric acid with a concentration of 1% by weight using a single wafer spin cleaning apparatus. Washing (ozone water / dilute hydrofluoric acid / ozone water / dilute hydrofluoric acid / ozone water / dilute hydrofluoric acid) was repeated alternately and three times with water and dilute hydrofluoric acid.
その後、オゾン水洗浄を１０秒行ない、表面に酸化膜を形成した後、純水リンスを９００秒行ない、その後、さらにオゾン水リンスを１０秒行ない、スピン回転により乾燥させた。 Thereafter, cleaning with ozone water was performed for 10 seconds, and after forming an oxide film on the surface, rinsing with pure water was performed for 900 seconds, and then rinsing with ozone water was further performed for 10 seconds, followed by drying by spin rotation.
前記のように処理したシリコンウエハについて、ＩＣＰ−ＭＳにより表面金属不純物濃度を調べた。表１にその結果を示す。
この結果は、前記実験例１に示した純水リンス時間９００秒の結果と比較して、純水リンスで付着した表面の金属不純物Ｎａ，Ｃａ，Ｚｎがオゾン水により除去することができた。
About the silicon wafer processed as mentioned above, the surface metal impurity density | concentration was investigated by ICP-MS. Table 1 shows the results.
Compared with the result of the pure water rinse time of 900 seconds shown in the experimental example 1, this result was that the metal impurities Na, Ca, Zn on the surface adhered by the pure water rinse could be removed by ozone water.
〔実験例３〕
更に、オゾン水リンスによる表面金属不純物の付着抑制の実験を行なった。
前記実験例１および実験例２と同様に、最終仕上げ研磨が成されたφ３００ｍｍシリコンウエハを、枚葉式スピン洗浄装置により濃度２０ｐｐｍのオゾン水と濃度１重量％の希フッ酸を用いて、各１０秒でオゾン水と希フッ酸とを３回交互に繰り返す洗浄（オゾン水／希フッ酸／オゾン水／希フッ酸／オゾン水／希フッ酸）を行なった。
その後、オゾン水リンスを０秒、５秒、１０秒、３０秒、６０秒、３００秒、および９００秒行ない、スピン回転により乾燥させた。
[Experimental Example 3]
Furthermore, an experiment was conducted to suppress adhesion of surface metal impurities by rinsing with ozone water.
In the same manner as in Experimental Example 1 and Experimental Example 2, φ300 mm silicon wafers subjected to final finish polishing were each treated with ozone water with a concentration of 20 ppm and dilute hydrofluoric acid with a concentration of 1% by weight using a single wafer spin cleaning apparatus. Washing (ozone water / dilute hydrofluoric acid / ozone water / dilute hydrofluoric acid / ozone water / dilute hydrofluoric acid) was repeated in 10 seconds, alternately with ozone water and dilute hydrofluoric acid three times.
Then, ozone water rinsing was performed for 0 seconds, 5 seconds, 10 seconds, 30 seconds, 60 seconds, 300 seconds, and 900 seconds, and dried by spin rotation.
前記のように処理したシリコンウエハについて、ＩＣＰ−ＭＳにより表面金属不純物濃度を調べた。その結果を表１に示す。
この実験例３の結果と実験例１の結果を対比することから明らかなように、前記純水リンスによる表面の金属不純物の増加に対して、オゾン水リンスでは表面の金属不純物の付着が抑制されることが認められた。
About the silicon wafer processed as mentioned above, the surface metal impurity density | concentration was investigated by ICP-MS. The results are shown in Table 1.
As is clear from the comparison between the results of Experimental Example 3 and the results of Experimental Example 1, the ozone water rinse suppresses the adhesion of metal impurities on the surface against the increase in surface metal impurities due to the pure water rinse. It was recognized that
〔実験例４〕
最後に、オゾン水のオゾン濃度による表面金属不純物の除去について実験を行なった。
前記実験例１、実験例２および実験例３と同様に、最終仕上げ研磨が成されたφ３００ｍｍシリコンウエハを、枚葉スピン洗浄装置により濃度２０ｐｐｍのオゾン水と濃度１重量％の希フッ酸を用いて、各１０秒でオゾン水と希フッ酸とを３回交互に繰り返す洗浄（オゾン水／希フッ酸／オゾン水／希フッ酸／オゾン水／希フッ酸）を行なった。その後、オゾン水洗浄を１０秒行ない、表面に酸化膜を形成した後、純水リンスを９００秒行ない、金属不純物濃度を強制的に高くして、さらにオゾン水製造装置のオゾン濃度調整により、それぞれ１、３、５、１０および２０ｐｐｍで調整したオゾン水によるリンスを１０秒行ない、スピン回転により乾燥させた。
[Experimental Example 4]
Finally, an experiment was conducted on the removal of surface metal impurities by the ozone concentration of ozone water.
Similar to Experimental Example 1, Experimental Example 2, and Experimental Example 3, the final finishing polishing was performed on a φ300 mm silicon wafer using ozone water with a concentration of 20 ppm and dilute hydrofluoric acid with a concentration of 1% by weight using a single wafer spin cleaning apparatus. Then, cleaning (ozone water / dilute hydrofluoric acid / ozone water / dilute hydrofluoric acid / ozone water / dilute hydrofluoric acid) was performed by repeating ozone water and dilute hydrofluoric acid three times alternately every 10 seconds. Then, after performing ozone water cleaning for 10 seconds, forming an oxide film on the surface, rinsing with pure water for 900 seconds, forcibly increasing the metal impurity concentration, and by adjusting the ozone concentration of the ozone water production device, Rinse with ozone water adjusted to 1, 3, 5, 10 and 20 ppm was performed for 10 seconds and dried by spin rotation.
前記のように処理したシリコンウエハについて、ＩＣＰ−ＭＳにより表面金属不純物濃度を調べた。その結果を表１に示す。
この実験例４の結果と実験例１の純水リンス時間９００秒の結果から明らかなように、金属不純物を除去する為には、オゾン水の濃度が５ｐｐｍ以上が望ましいとすることが認められた。ただし、オゾン水の濃度５ｐｐｍ未満であっても処理時間を長くすることにより同様の効果が得られるが、この場合、処理時間が長くなることによりパーティクルが付着する危険性が高くなる、装置のスループットが遅くなるなど、不都合を生じる可能性がある。
About the silicon wafer processed as mentioned above, the surface metal impurity density | concentration was investigated by ICP-MS. The results are shown in Table 1.
As is clear from the results of Experimental Example 4 and the pure water rinsing time of 900 seconds of Experimental Example 1, it was recognized that the concentration of ozone water is preferably 5 ppm or more in order to remove metal impurities. . However, even if the concentration of ozone water is less than 5 ppm, the same effect can be obtained by increasing the processing time. In this case, the risk of adhesion of particles increases due to the longer processing time. May cause inconveniences such as slowing down.
本発明は、枚葉式スピン洗浄法に限らず、バッチ式洗浄法にも適用することができ、広くシリコンウエハの洗浄に用いることができる。 The present invention can be applied not only to the single wafer spin cleaning method but also to the batch cleaning method, and can be widely used for cleaning silicon wafers.
Ｓ１ ステップ１
Ｓ２ ステップ２
Ｓ３ ステップ３
Ｓ４ ステップ４
Ｓ５ ステップ５
Ｓ６ ステップ６
S1 Step 1
S2 Step 2
S3 Step 3
S4 Step 4
S5 Step 5
S6 Step 6
Claims (2)
前記シリコンウエハを洗浄する工程の後、前記薬液を用いて洗浄されたシリコンウエハの表面をオゾン水でリンスすることにより、前記シリコンウエハ表面に酸化膜を形成する第１のオゾン水リンス工程と、
前記第１のオゾン水リンス工程の後、前記第１のオゾンリンス工程で形成された酸化膜表面を純水でリンスする純水リンス工程と、
前記純水でリンスした後、純水でリンスされた酸化膜表面を再びオゾン水でリンスすることによって、前記純水リンス工程においてウエハの酸化膜表面で金属水酸化物となった金属不純物を除去する第２のオゾン水リンス工程と、
前記第２のオゾン水リンス工程の後、前記金属不純物が除去されたシリコンウエハを乾燥する乾燥工程と、
を含むことを特徴とするシリコンウエハの洗浄方法。 A step of cleaning the silicon wafer by alternately applying ozone water and dilute hydrofluoric acid, or using a mixed solution of NH 4 OH, H 2 O 2 and H 2 O ;
After the step of cleaning the silicon wafer, a first ozone water rinsing step of forming an oxide film on the silicon wafer surface by rinsing the surface of the silicon wafer cleaned with the chemical solution with ozone water;
After the first ozone water rinsing step, a pure water rinsing step of rinsing the oxide film surface formed in the first ozone rinsing step with pure water;
After rinsing with pure water, the surface of the oxide film rinsed with pure water is again rinsed with ozone water, thereby removing metal impurities that have become metal hydroxide on the oxide film surface of the wafer in the pure water rinsing step. A second ozone water rinsing step,
A drying step of drying the silicon wafer from which the metal impurities have been removed after the second ozone water rinsing step;
A method for cleaning a silicon wafer, comprising:
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